A conventional thermal module is mainly composed of a heat dissipation base seat and heat pipes passing through the heat dissipation base seat. The heat pipes are generally securely affixed to the heat dissipation base seat by means of welding. However, in the case that the heat dissipation base seat and the heat pipes are made of different metal materials with different performances, (for example, the heat pipes are made of copper material, while the radiating fins are made of aluminum material), it will be hard to securely connect the heat dissipation base seat with the heat pipes. This is because an aluminum material can be hardly connected with other kinds of materials by means of common welding process. An aluminum material can be welded with another aluminum material by means of some special welding processes (such as argon welding). However, the aluminum material cannot be welded to a copper material with different performances by means of argon welding. Therefore, prior to the welding process, it is necessary first coat the aluminum-made radiating fins with a coating to facilitate the successive welding process. Such procedure is quite troublesome.
In some other cases, the heat dissipation base seat is formed with perforations or channels for receiving the heat pipes that are connected with the heat dissipation base seat. In such thermal module, the heat dissipation base seat is in contact with a heat source to absorb the heat generated by the heat source and then transfer the heat to the heat pipe. Such thermal module has a heat conduction efficiency much lower than that of a thermal module in which the heat pipes are in direct contact with the heat source. Moreover, the thermal module with the heat dissipation base seat has a heavier weight and larger volume and is manufactured at higher cost as a whole. It is inconvenient to install or transfer such thermal module. Therefore, such thermal module can be hardly applied to an electronic device with narrow interior space.
Therefore, the conventional thermal module has the following shortcomings:    1. The heat conduction efficiency is poor.    2. The manufacturing cost is higher.    3. The application site is limited.